Powered cutting tool

ABSTRACT

A cutting tool includes a housing and a pair of cutting blades at least partially extending from the housing. At least a first of the cutting blades is movable. The cutting tool also includes a drive mechanism including a cam and a ratchet mechanism. At least a portion of the ratchet mechanism is drivably coupled to the first cutting blade. The cutting tool further includes a motor for providing torque to the cam to actuate the ratchet mechanism. The ratchet mechanism includes a follower that is translatable in a direction transverse to a rotational axis of the cam in response to rotation of the cam.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/855,307 filed on Apr. 2, 2013, which claims priority U.S. ProvisionalPatent Application No. 61/621,846 filed Apr. 9, 2012, and which is acontinuation-in-part of International Patent Application No.PCT/US2011/055465 filed Oct. 7, 2011, which claims priority to U.S.Provisional Patent Application Nos. 61/391,170 filed Oct. 8, 2010;61/431,099 filed Jan. 10, 2011; and 61/474,062 filed Apr. 11, 2011, theentire contents of all of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to power tools, and more particularly tobattery-powered cutting tools.

BACKGROUND OF THE INVENTION

Non-powered cable-cutting tools typically include opposed cutting bladesattached to respective elongated handles. The blades are pivotablyattached, such that squeezing the handles together results inprogressive closing of the gap between the cutting blades to cut a cablepositioned between the blades. Such non-powered cable-cutting tools maybe difficult to use with some materials or cable sizes due toinsufficient leverage provided by the handles to ensure a complete andstraight cut. Such non-powered cable-cutting tools may also be difficultto use for some individuals lacking sufficient wrist strength togenerate enough force on the handles to cut a particular size ormaterial of cable.

SUMMARY OF THE INVENTION

The invention provides, in one aspect, a cutting tool including ahousing and a pair of cutting blades at least partially extending fromthe housing. At least a first of the cutting blades is movable. Thecutting tool also includes a drive mechanism including a cam and aratchet mechanism. At least a portion of the ratchet mechanism isdrivably coupled to the first cutting blade. The cutting tool furtherincludes a motor for providing torque to the cam to actuate the ratchetmechanism. The ratchet mechanism includes a follower that istranslatable in a direction transverse to a rotational axis of the camin response to rotation of the cam.

Other features and aspects of the invention will become apparent byconsideration of the following detailed description and accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a cutting tool according to anembodiment of the invention.

FIG. 2 is an exploded, front perspective view of the cutting tool ofFIG. 1.

FIG. 3 is a cutaway perspective view of the cutting tool of FIG. 1.

FIG. 4 is a partial cross-sectional view of a multi-speed planetarytransmission of the cutting tool of FIG. 1, illustrating thetransmission in a high-speed mode.

FIG. 5 is a partial cross-sectional view of the multi-speed planetarytransmission of FIG. 4, illustrating the transmission in a low-speedmode.

FIG. 6 is a side view of a cam and a ratchet mechanism of the cuttingtool of FIG. 1, illustrating the ratchet mechanism incrementally closingthe blades of the cutting tool.

FIG. 7 is a side view of the cam and ratchet mechanism of FIG. 6,illustrating the ratchet mechanism being released to open the blades ofthe cutting tool.

FIG. 8 is an enlarged, front perspective view of the cutting tool ofFIG. 1.

FIG. 9 is a cross-sectional view of the cutting tool taken along line9-9 in FIG. 8.

FIG. 10 is a side view of a cutting tool according to another embodimentof the invention, illustrating a cam and a ratchet mechanism.

FIG. 11 is an enlarged view of a portion of the ratchet mechanism shownin FIG. 10.

FIG. 12 is a schematic illustrating an electronic braking circuit and acurrent overload circuit for use in either of the embodiments of thecutting tool shown in FIGS. 1 and 10.

FIG. 13 is a schematic illustrating a reversing circuit and a currentoverload circuit for use in either of the embodiments of the cuttingtool shown in FIGS. 1 and 10.

FIG. 14 is a schematic illustrating a direction switch and a shuttle foruse in either of the embodiments of the cutting tool shown in FIGS. 1and 10.

Before any embodiments of the invention are explained in detail, it isto be understood that the invention is not limited in its application tothe details of construction and the arrangement of components set forthin the following description or illustrated in the following drawings.The invention is capable of other embodiments and of being practiced orof being carried out in various ways. Also, it is to be understood thatthe phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting.

DETAILED DESCRIPTION

FIG. 1 illustrates a powered cable-cutting tool 10. The tool 10 includesa housing 12 and a pair of cutting blades 14, 18 at least partiallyextending from the housing 12. In the illustrated embodiment of the tool10, each of the blades 14, 18 is shaped having a curved cutting edge 22.Alternatively, one or both of the blades 14, 18 may include a straightcutting edge. Furthermore, one or both of the blades 14, 18 may includeone or more support portions sized to accommodate different cablediameters of standard sizes. Also, in the illustrated embodiment of thetool 10, the blades 14, 18 are offset with respect to a vertical planepassing through the middle of the housing 12. Alternatively, theposition of the blades 14, 18 may coincide with the vertical planepassing through the middle of the housing 12.

With reference to FIG. 2, the cutting blades 14, 18 are pivotablycoupled by an output shaft 26 that is rotatably supported within thehousing by spaced bushings 30 (see also FIG. 9). In the illustratedembodiment of the tool 10, the lower blade 18 (i.e., from the frame ofreference of FIGS. 1 and 2) is fixed to the housing 12 while the upperblade 14 is coupled for co-rotation with the shaft 26. Particularly, theoutput shaft 26 includes a first spline portion 210 that is receivedwithin a corresponding shaped aperture 214 in the upper blade 14. Thefirst spline portion 210 is asymmetrical in that a locating spline 218on the first spline portion 210 has a width different than that of theremaining splines on the spline portion 210. As such, the upper blade 14may be fit to the shaft 26 in only a single orientation. Duringoperation of the tool 10, the output shaft 26 is rotated within thehousing 12 (i.e., in a clockwise direction from the frame of referenceof FIG. 3) to pivot the upper blade 14 relative to the lower blade 18 tothereby close the gap between the blades 14, 18 and perform a cuttingoperation. Alternatively, both of the blades 14, 18 may be movablerelative to the housing 12 when performing a cutting operation.

With reference to FIG. 2, the lower blade 18 is prevented from pivotingrelative to the housing 12 by a securing member (e.g., in theillustrated construction of the tool 10, a cap screw 32) having a headthat is received within a stepped aperture 33 in the lower blade 18. Thestepped aperture 33 has a diameter nominally larger than a diameter of ahead of the cap screw 32. When the head of the cap screw 32 is removedfrom the aperture 33, the lower blade 18 is permitted to pivot away fromthe upper blade 14 a limited amount about the output shaft 26 (e.g., 5degrees; FIG. 8) to clear any jams that might occur between theworkpiece and the blades 14, 18. Alternatively, the securing member maybe configured in any of a number of different manners (e.g., a tool-lessclamp, etc.) to selectively permit the lower blade 18 to be pivoted alimited amount to clear any jams that might occur between the workpieceand the blades 14, 18.

With reference to FIG. 1, the tool 10 also includes an on-board toolstorage arrangement 228 for carrying one or more hand tools (e.g., a hexkey 230) for loosening and tightening the cap screw 32. Particularly,the arrangement 228 includes a through-hole 234 in the housing 12 inwhich one segment of the hex key 230 may be received, and a clamp 238 inwhich the other segment of the hex key 230 is secured. Another hex key230 may be supported on the other side of the housing 12 not shown inFIG. 1.

With reference to FIG. 9, the output shaft 26 includes a shoulder 29 formaintaining a gap between the blades 14, 18 during operation of the tool10. For example, such a gap may be between about 0.005 inches and about0.010 inches in length.

With reference to FIGS. 2 and 3, the tool 10 includes an electric motor34 positioned within the housing 12. The motor 34 may be powered by anon-board power source (e.g., a battery 36) or a remote power source(e.g., an electrical outlet) via a power cord. The tool 10 also includesa switch 37 selectively electrically connecting the power source and themotor 34. The switch 37 is actuated by a pull trigger 35 which, in turn,is engageable by a user of the tool 10 during the normal course ofoperation of the tool 10. The tool 10 may also include a controllerelectrically connected to the switch 37 and the motor 34 to providevaried operation of the motor 34 in response to actuation of the switch37 (e.g., a variable speed operation, etc.).

With reference to FIGS. 1-3, the tool 10 also includes a trigger lock182 that must be actuated before the trigger 35 may be pulled toactivate the motor 34. The trigger lock 182 includes a first lever 186that is pivotably coupled to the housing 12 (FIG. 3). The first lever186 includes opposed projections 190 that extend from opposite sides ofthe housing 12, respectively, to be accessible to the user of the tool10 (see also FIG. 1). The trigger lock 182 also includes a second lever194 that is pivotably coupled to the housing 12 (FIG. 3). The firstlever 186 is engageable with a first arm 198 of the second lever 194 topivot the second lever 194 from a first position, in which a second arm202 of the lever 194 blocks actuation of the trigger 35, toward a secondposition, in which the second arm 202 is cleared of the trigger 35.Therefore, in operation of the tool 10, a user must depress one of theprojections 190 to pivot the first lever 186 clockwise, from the frameof reference of FIG. 3, to engage and pivot the second lever 194 fromthe first position to the second position prior to pulling the trigger35.

With continued reference to FIGS. 2 and 3, the tool 10 further includesa transmission 38 configured to receive torque from the motor 34 andprovide an output having an increased torque at a reduced rotationalspeed compared to the output of the motor 34. In the illustratedembodiment of the tool 10, the transmission 38 includes a transmissionhousing 39 having respective portions 39 a, 39 b that are secured in aclamshell arrangement (FIG. 2). Particularly, the transmission housingportion 39 a includes a plurality of nuts 40 supported therein, whilethe other transmission housing portion 39 b includes a correspondingplurality of bolts 41 supported therein for threadably engaging the nuts40 in the portion 39 a. The motor 34 is thereby clamped between thetransmission housing portions 39 a, 39 b using the same fasteners 40,41. The transmission housing portions 39 a, 39 b are also made ofdifferent materials to provide a higher yield strength to the portion 39b to which the fixed lower blade 18 is mounted. Specifically, thetransmission housing portion 39 b is made from an alloy having anincreased Zinc content compared to the alloy used in making thetransmission housing portion 39 a.

With continued reference to FIG. 2, the tool 10 includes a light 206(e.g., an LED) on the transmission housing 39 for illuminating the areaon a workpiece to be cut. In the illustrated embodiment of the tool 10,the light 206 is positioned adjacent the upper blade 14 on a side of thetransmission housing portion 39 b facing the blades 14, 18.Alternatively, the light 206 may be positioned elsewhere on the tool 10.In operation of the tool 10, the light 206 is activated in response tothe trigger 35 being depressed, and remains on for a period of timeafter the trigger 35 is released. The light 206 may also be activatedseparately from the motor 34 by only slightly depressing the trigger 35.

In the illustrated embodiment of the tool 10, the transmission 38 isconfigured as a planetary transmission 38 having a plurality of stages,one of which may be deactivated to provide a multi-speed output. Forexample, the illustrated transmission 38 includes four planetary stages,the first 38 a, second 38 b, and fourth stages 38 d of which remainactive at all times, while the third planetary stage 38 c may beselectively deactivated by the user of the tool 10 to use the tool 10 ina high speed mode (FIG. 4). The third planetary stage 38 c may bedeactivated, for example, by adjusting an outer ring gear 43 of thethird planetary stage 38 c such that it co-rotates with a carrier 44 ofthe second planetary stage 38 b. Consequently, the planet gears and thecarrier of the third planetary stage 38 c would also co-rotate with thecarrier 44 of the second planetary stage 38 b, thereby transferring therotational output of the carrier 44 of the second planetary stage 38 bthrough all of the components of the third planetary stage 38 c withoutany additional speed reduction.

The third planetary stage 38 c may be activated by adjusting the outerring gear 43 of the third planetary stage 38 c such that it is fixedrelative to the housing 12 (FIG. 5). Particularly, the outer ring gear43 includes a plurality of teeth 45 that are engaged with correspondingteeth 47 on an internal surface of an outer ring gear 48 of the fourthplanetary stage 38 d which, in turn, is rotatably fixed to thetransmission housing 39 by a plurality of protrusions 49 on the outerperiphery of the outer ring gear 48 that are received withincorresponding recesses 51 in the transmission housing 39 (FIG. 3).Accordingly, when the outer ring gear 43 is shifted to the positionshown in FIG. 5, the planet gears of the third planetary stage 38 c maybe driven by the carrier 44 of the second planetary stage 38 b to “walk”about the inner periphery of the outer ring gear 43, thereby rotatingthe carrier of the third planetary stage 38 c at a reduced rotationalspeed compared to the carrier of the second planetary stage 38 b. Thetool 10, therefore, may be used in a low speed mode.

With reference to FIG. 2, rubber bumpers 55 are positioned adjacent thetop and bottom protrusions 49 on the outer ring gear 48 of the fourthplanetary stage 38 d to absorb reverse impact loading to thetransmission 38 during operation of the tool 10.

The outer ring gear 43 of the third planetary stage 38 c is adjusted ormanipulated between the configurations described above by an actuator 52that at least partially protrudes through the housing 12. In theillustrated embodiment of the tool 10, the actuator 52 is configured asa slide switch 52 that is movable between a first position, in which thethird planetary stage 38 c is active for providing a low speed mode ofthe tool 10, and a second position, in which the third planetary stage38 c is inactive to provide a high speed mode of the tool 10. A pivotingwire 53 is positioned between the slide switch 52 and the outer ringgear 43 for transferring the linear movement of the slide switch 52 tothe outer ring gear 43 between the above-described positions forproviding the high speed and low speed modes of the tool 10.Particularly, opposite ends 56 of the wire 53 slide within acircumferential groove 60 in the outer ring gear 43, therebyfacilitating linear movement of the outer ring gear 43 while permittingrotation of the outer ring gear 43 in the high speed mode of the tool10.

With reference to FIGS. 2 and 3, the tool 10 also includes a drivemechanism 42 including a cam 46 and a ratchet mechanism 50 drivablycoupling the transmission 38 and the upper blade 14. As shown in FIG. 2,the cam 46 includes a lobe 54 having a cam surface 58 and a shaft 62fixed for co-rotation with the lobe 54 (using, for example, aninterference fit, by integrally forming or molding, etc.; FIGS. 4 and5). Opposite ends 66 of the shaft 62 are rotatably supported by thetransmission housing 39 by respective bushings 70. One end 66 of theshaft 62 includes a non-circular cross-sectional shape, and an outputcarrier 74 of the fourth planetary stage 38 d includes an aperture 75having a corresponding shape in which the end 66 of the shaft 62 isreceived. As such, a driving connection is established between the shaft62 and the transmission 38. The cam surface 58 is spaced from arotational axis 78 of the shaft 62 by a varying distance to imparttranslation to a portion of the ratchet mechanism 50, in a directionsubstantially normal to the direction of the rotational axis 78, inresponse to rotation of the cam 46. It should be understood that the cam46 may be configured differently than that shown in the drawings. Forexample, the cam 46 may be configured as an eccentric pin on a rotatingarm (e.g., for use with a scotch-yoke mechanism).

With reference to FIGS. 2 and 3, the ratchet mechanism 50 includes aratchet 82 drivably coupled to the upper blade 14 via the output shaft26. Particularly, the output shaft 26 includes a second spline portion222 that is received within a corresponding shaped aperture 226 in theratchet 82. The second spline portion 222 is asymmetrical in that alocating spline (not shown) on the second spline portion 222 has a widthdifferent than that of the remaining splines on the spline portion 222.As such, the ratchet 82 may be fit to the shaft 26 in only a singleorientation. As such, the ratchet 82 is coupled for co-rotation with theupper blade 14 and the output shaft 26. The ratchet 82 is substantiallyarc-shaped and includes teeth 86. The ratchet 82 also includesrespective grooves 88 in opposite faces of the ratchet 82 in whichcorresponding tension springs 85 are received (FIG. 2). One end of eachspring 85 is anchored to the transmission housing 39, while the otherend of each spring 85 is fixed to the ratchet 82. As such, the springs85 bias the ratchet 82 in a clockwise direction from the frame ofreference of FIGS. 6 and 7. The ratchet mechanism 50 also includesparallel links 90, each of which includes a first end 94 pivotablycoupled to the output shaft 26 and a second end 98 that is movable inresponse to rotation of the cam 46. A tension spring 100 couples thelinks 90 and the transmission housing 39 for biasing the links 90 towarda default or “home” position shown in FIG. 3.

The ratchet mechanism 50 further includes a first, driven pawl 102coupled to each of the links 90 between the first and second ends 94, 98(FIG. 2). More particularly, the pawl 102 includes a support shaft 106extending from each side of the pawl 102 that is received withinrespective apertures in the links 90. As such, the pawl 102 is pivotablycoupled to the links 90. As is discussed in more detail below, the pawl102 is pivoted between a first position, in which the pawl 102 isengaged with the ratchet 82, and a second position, in which the pawl102 is disengaged from the ratchet 82.

The pawl 102 also includes teeth 110 that are selectively engaged withthe teeth 86 on the ratchet 82. With reference to FIG. 6, the teeth 86,110 on the respective ratchet 82 and pawl 102 are shaped such that, inresponse to rotation of the pawl 102 and the links 90 about the outputshaft 26 in a clockwise direction from the frame of reference of FIG. 6,the pawl 102 is prevented from sliding relative to the ratchet 82. Theengaged ratchet 82 and pawl 102, therefore, co-rotate about a rotationalaxis 114 of the output shaft 26. However, the pawl 102 is permitted toslide relative to the ratchet 82 in response to rotation of the pawl 102and the links 90 about the output shaft 26 in a counter-clockwisedirection from the frame of reference of FIG. 6.

With reference to FIGS. 2 and 3, the ratchet mechanism 50 furtherincludes a follower 118 pivotably coupled to the second end 98 of eachof the links 90 and engaged with the cam 46. A pin 122 is receivedwithin respective apertures in the links 90 and the follower 118 topivotably couple the links 90 and the follower 118. Opposite ends of thepin 122 are trapped within respective slots 124 in the transmissionhousing 39 (FIG. 2) configured to permit only vertical movement of thepin 122 within the slots 124 (i.e., relative to the frame of referenceof FIG. 6). In other words, the pin 122, and therefore the ends 98 ofthe respective links 90, is prevented from translating relative to thetransmission housing 39 in any other direction.

In the illustrated embodiment of the tool 10, the follower 118 includesa roller 126 engaged with the cam 46 (FIG. 2). The roller 126 isrotatably supported by a pin 130, which includes opposite ends trappedwithin respective slots 128 in the transmission housing 39 (FIG. 2)configured to permit only vertical movement of the pin 130 within theslots 128 (i.e., relative to the frame of reference of FIG. 6). In otherwords, the pin 130, and therefore the follower 118, is prevented fromtranslating relative to the transmission housing 39 in any otherdirection.

With reference to FIG. 2, the ratchet mechanism 50 also includes asecond, follower pawl 134 pivotably coupled to the transmission housing39 and engaged with the ratchet 82. More particularly, the pawl 134 issupported on a support shaft 138 having opposite ends of which that arepivotably supported by the transmission housing 39. An arm 140 is alsocoupled to the support shaft 138 for co-rotation with the support shaft138 and the pawl 134. In the illustrated embodiment of the tool 10, thepawl 134, the support shaft 138, and the arm 140 are integrally formedas a single piece. The tool 10 also includes a biasing member (e.g., acompression spring 141) that biases the pawl 134 in a clockwisedirection from the frame of reference of FIGS. 6 and 7 for engaging thepawl 134 and the ratchet 82. As is discussed in more detail below, thefollower pawl 134 is pivoted between a first, biased position, in whicha tip 142 of the pawl 134 is engaged with the ratchet 82, and a secondposition against the bias of the spring 141, in which the pawl 134 isdisengaged from the ratchet 82.

With reference to FIG. 2, the tool 10 includes an actuator 146 coupledto both of the pawls 102, 134. More particularly, the actuator 146includes a first cam lobe 148 engageable with the driven pawl 102 via alever 152 coupled for co-rotation with one of the support shafts 106(e.g., via an interference fit with a portion of the support shaft 106),and a second cam lobe 156 engageable with the follower pawl 134 via thearm 140 on the support shaft 138. The actuator 146 is biased toward theleft from the frame of reference of FIG. 6 by the compression spring 141via the interaction between the second cam lobe 156 and the arm 140. Theactuator 146, therefore, would be movable (i.e., forward or to the rightfrom the frame of reference of FIG. 6) between a first position againstthe bias of the spring 141 in which the driven and follower pawls 102,134 are permitted to engage the ratchet 82 (FIG. 6), and a secondposition in which the actuator 146 disengages the driven and followerpawls 102, 134 from the ratchet 82 (FIG. 7). When moving the actuator146 from the first position to the second position, the driven andfollower pawls 102, 134 would be pivoted in a counter-clockwisedirection from the frame of reference of FIG. 7 to disengage therespective pawls 102, 134 from the ratchet 82 to permit the gap betweenthe blades 14, 18 to be re-opened in preparation for another cuttingoperation.

In the illustrated embodiment of the tool 10, a trigger 160 is pivotablycoupled to the transmission housing 39 and includes a branch portion 164that is received within a corresponding slot 168 in the actuator 146 anda trigger portion 172 that is engageable by a user of the tool 10. Thetool 10 also includes a biasing member (e.g., a torsion spring 176) thatbiases the trigger 160 in a counter-clockwise direction from the frameof reference of FIG. 7 to permit the compression spring 141, via thepawl 134 and arm 140, to return the actuator 146 to its “home” positionshown in FIG. 6. The trigger 160 may then be pivoted in a clockwisedirection from the frame of reference of FIG. 7 to engage the actuator146 and move the actuator 146 toward its second position. Alternatively,the actuator 146 may be moved between its first and second positionsusing any of a number of different mechanisms that protrude from thehousing 12 to be easily accessible to the user of the tool 10.

To perform a cutting operation with the tool 10, the user would firstplace a cable or other workpiece within the gap between the blades 14,18 (FIG. 6). The switch 37 is then actuated (e.g., by pulling thetrigger 35, etc.) to activate the motor 34 which, in turn, drives thetransmission 38 and the cam 46. As the cam 46 is rotated in acounter-clockwise direction from the frame of reference of FIG. 2, theroller 126 rides along the cam surface 58 and is displaced upwardly withthe follower 118 as the location of maximum lift is approached. Becausethe links 90 are pivotably supported on the output shaft 26 (which ispivotably supported by the transmission housing 39), the links 90 andthe driven pawl 102 are pivoted away from their home position in aclockwise direction from the frame of reference of FIG. 6 about the axis114 of the output shaft 26, thereby causing the driven pawl 102 (whichis engaged with the ratchet 82) to incrementally rotate the ratchet 82,the output shaft 26, and the upper blade 14 about the axis 114 of theoutput shaft 26. The shape of the teeth 86 on the ratchet 82 alsopermits the ratchet 82 to slide relative to the follower pawl 134, withthe tip 142 of the pawl 134 being successively moved between adjacentteeth 86, as the ratchet 82 is driven in a clockwise direction about theaxis 114 of the output shaft 26. Therefore, the follower pawl 134 locksthe upper blade 14 in successive positions relative to the lower blade18 coinciding with the spacing between adjacent teeth 86 on the ratchet82, and prevents the upper blade 14 from rotating relative to the lowerblade 18 in a counter-clockwise direction.

After the follower 118 passes over the location of maximum lift on thecam 46, the links 90 and the driven pawl 102 are permitted to rotate ina counter-clockwise direction from the frame of reference of FIG. 6about the axis 114 of the output shaft 26, toward the home position ofthe links 90, while the follower pawl 134 maintains the upper blade 14in position relative to the lower blade 18. As previously discussed, theshape of the teeth 86, 110 on the respective ratchet 82 and driven pawl102 permit the driven pawl 102 to slide relative to the ratchet 82 asthe links 90 return to their home position. Continued rotation of thecam 46 again causes the follower 118 to be upwardly displaced as thelocation of maximum lift is approached, thereby causing the driven pawl102 to incrementally rotate the ratchet 82, the output shaft 26, and theupper blade 14 in a clockwise direction to further close the gap betweenthe blades 14, 18. This process is continued until the gap issufficiently closed to complete the cutting operation on the cable orother workpiece.

The ratchet 82 includes an aperture in which a stop member (e.g., a pin178; FIG. 3) is received that is engageable with at least one of theparallel links 90 to limit the extent to which the ratchet 82, andtherefore the upper blade 14, may be pivoted relative to the housing 12in a clockwise direction from the frame of reference of FIG. 6.Alternatively, the stop member may be configured in any of a number ofdifferent manners.

After the cutting operation is complete, the user may depress thetrigger 160 to slide the actuator 146 toward its second position shownin FIG. 7 to pivot both the driven pawl 102 and the follower pawl 134 ina counter-clockwise direction from the frame of reference of FIG. 7 todisengage the ratchet 82. The ratchet 82, the output shaft 26, and theupper blade 14 may then be pivoted counter-clockwise (e.g., by thereturn springs 85) to re-open the gap between the blades 14, 18 inpreparation for another cutting operation. The user may then release thetrigger 160 to permit the actuator 146 to be returned to the firstposition shown in FIG. 6 by the compression spring 141 (via theinteraction with the arm 140) to permit the driven and follower pawls102, 134 to re-engage the ratchet 82. Because the trigger 160 ispositioned proximate the trigger 35, the user of the tool 10 may usetheir same hand for pulling the trigger 160 as that used when pullingthe trigger 35.

FIG. 10 illustrates a tool 10 a in accordance with another embodiment ofthe invention. As such, like features are shown with like referencenumerals with the letter “a.” The ratchet teeth 86 a and the pawl teeth110 a, however, are each defined by adjacent first and second edges orsurfaces defining included angles A1, A2 therebetween of at least about75 degrees (see also FIG. 11). Particularly, the included angle A1between the first and second surfaces of each of the ratchet teeth 86 ais at least about 85 degrees, and the included angle A2 between thefirst and second surfaces of each of the pawl teeth 110 a is at leastabout 90 degrees. The respective shapes of the ratchet teeth 86 a andthe pawl teeth 110 a facilitate pivoting of the pawl 102 a away from theratchet 82 a when a reaction torque is applied to the ratchet 82 aduring use of the tool 10 a that inhibits further closing of the cuttingblades 14 a, 18 a and that might otherwise tend to bind the pawl 102 ato the ratchet 82 a in absence of teeth 86 a, 110 a being shaped in theabove-described manner. Such a reaction torque may develop or be appliedto the ratchet 82 a in response to the blades 14 a, 18 a seizing whileclosing on a material not approved for use with the tool 10 a (e.g., asteel rod). Because the included angles A1, A2 of the teeth 86 a, 110 aare sized in the manner described above, the pawl 102 a may be pivotedaway from the ratchet 82 a in response to actuation of the trigger 160 awithout substantial binding between the ratchet teeth 86 a and the pawlteeth 110 a. The movable blade 14 a may then be pivoted to an openposition to remove the unapproved material from the blades 14 a, 18 a.

The tool 10 may also include electronics for alleviating binding betweenthe ratchet 82 and the pawl 102 that might occur in response to theblades 14, 18 seizing while closing on a material not approved for usewith the tool 10. As such, the user may actuate the trigger 160 withoutmuch effort to pivot the pawl 102 away from the ratchet 82 and releasethe movable blade 14 from the remainder of the ratchet mechanism 50 tore-open the blade 14 and remove the unapproved material from the blades14, 18. Although not described in detail, the tool 10 a may also includesimilar electronics.

For example, as shown in FIG. 12, the tool 10 may include an electronicbraking circuit 300 for normally providing a braking force to the motor34 in response to deactivation of the motor 34, and a current overloaddetection circuit 304 for monitoring an amount of electrical currentdrawn by the motor 34 when the motor 34 is activated. The currentoverload detection circuit 304 may both deactivate the motor 34 andoverride the electronic braking circuit 300 in response to the motor 34exceeding a threshold electrical current to prevent application of thebraking force to the motor 34. Therefore, because the motor 34 is freelyrotatable subsequently to being deactivated, the motor 34 may betemporarily and briefly rotated in a reverse direction by a torquedirected through the transmission 38 and the cam 46, and generated bysliding and/or rolling contact between the follower 118 and the cam 46as a result of the tension spring 100 exerting a linear return force onthe links 90. As such, the user may actuate the trigger 160 without mucheffort to pivot the pawl 102 away from the ratchet 82 and release themovable blade 14 from the remainder of the ratchet mechanism 50 tore-open the blade 14 and remove the unapproved material from the blades14, 18.

Alternatively, as shown in FIG. 13, the tool 10 may include a reversingcircuit 308 for temporarily and briefly reversing a rotational directionof the motor 34 in response to at least one of the motor 34 exceeding athreshold electrical current (i.e., as detected by a current overloaddetection circuit 304 such as that described above) and actuation of theswitch 37 coinciding with the user releasing the trigger 35. As themotor 34 is reversed, the transmission 38 and the cam 46 are alsoreversed, thereby enabling the tension spring 100 to pivot the links 90toward their home position (FIG. 7) and relieve pressure or bindingbetween the ratchet 82 and the pawl 102 prior to disengaging the pawl102 from the ratchet 82. Thereafter, the user may actuate the trigger160 without much effort to pivot the pawl 102 away from the ratchet 82and release the movable blade 14 from the remainder of the ratchetmechanism 50 to re-open the blade 14 and remove the unapproved materialfrom the blades 14, 18.

As a further alternative, as shown in FIG. 14, the tool 10 may include adirection switch 312 that is electrically connected with the motor 34and the switch 37. The direction switch 312 may be actuated between afirst position in which the motor 34 and the cam 46 are driven in aforward direction to actuate the ratchet mechanism 50 and incrementallyclose the blades 14, 18 during a cutting operation, and a secondposition in which the motor 34 and the cam 46 are driven in a reversedirection. The tool 10 may include a shuttle 316, similar to theactuator 52 shown in FIG. 1, for toggling the direction switch 312between the first and second positions. Particularly, the shuttle 316and/or direction switch 312 may be biased toward the first position(e.g., by a spring 320) such that the user must continuously depress theshuttle 316 to maintain the direction switch 312 in the second position,while depressing the trigger 35, in order to operate the motor 34 in areverse direction. As the motor 34 and the cam 46 are reversed, thetension spring 100 pivots the links 90 toward their home position (FIG.7) and relieves pressure or binding between the ratchet 82 and the pawl102 prior to disengaging the pawl 102 from the ratchet 82. Thereafter,the user may actuate the trigger 160 without much effort to pivot thepawl 102 away from the ratchet 82 and release the movable blade 14 fromthe remainder of the ratchet mechanism 50 to re-open the blade 14 andremove the unapproved material from the blades 14, 18.

Various features of the invention are set forth in the following claims.

What is claimed is:
 1. A cutting tool comprising: a housing; a pair ofcutting blades at least partially extending from the housing, at least afirst of the cutting blades is movable; a drive mechanism including acam and a ratchet mechanism, at least a portion of the ratchet mechanismis drivably coupled to the first cutting blade; a motor for providingtorque to the cam to actuate the ratchet mechanism; and a planetarytransmission between the motor and the cam, the transmission including acarrier directly connected to the cam, wherein the ratchet mechanismincludes a follower that is translatable in a direction transverse to arotational axis of the cam in response to rotation of the cam.
 2. Thecutting tool of claim 1, wherein a second of the cutting blades is fixedrelative to the housing.
 3. The cutting tool of claim 1, furthercomprising an output shaft rotatably supported within the housing,wherein the first cutting blade is coupled for co-rotation with theoutput shaft, and wherein a second of the cutting blades is pivotablysupported by the output shaft.
 4. The cutting tool of claim 3, furthercomprising a securing member that is movable between a first position,in which the second cutting blade is secured relative to the housing,and a second position, in which limited pivoting movement of the secondcutting blade about the output shaft is permitted.
 5. The cutting toolof claim 3, wherein the output shaft includes a shoulder for maintaininga gap between the cutting blades.
 6. The cutting tool of claim 1,further comprising an output shaft rotatably supported within thehousing, wherein the first cutting blade is coupled for co-rotation withthe output shaft, and wherein the ratchet mechanism includes a ratchetcoupled for co-rotation with the first cutting blade, a link having afirst end pivotably coupled to the output shaft and a second end that ismovable in response to rotation of the cam, and a pawl coupled to thelink between the first and second ends and engaged with the ratchet. 7.The cutting tool of claim 6, wherein the follower is pivotably coupledto the second end of the link and engaged with the cam.
 8. The cuttingtool of claim 7, wherein the follower includes a roller engaged with thecam.
 9. The cutting tool of claim 6, wherein the pawl is pivotablycoupled to the link and movable between a first position, in which thepawl is engaged with the ratchet, and a second position, in which thepawl is disengaged from the ratchet.
 10. The cutting tool of claim 6,wherein the pawl is a first pawl, and wherein the ratchet mechanismfurther includes a second pawl pivotably coupled to the housing andengaged with the ratchet.
 11. The cutting tool of claim 10, furthercomprising an actuator engageable with the first and second pawls, andwherein the actuator is movable between a first, biased position inwhich the first and second pawls are permitted to engage the ratchet,and a second position in which the actuator disengages the first andsecond pawls from the ratchet.
 12. The cutting tool of claim 11, whereinthe ratchet mechanism further includes a lever coupled for co-rotationwith the first pawl, a support shaft upon which the second pawl iscoupled for co-rotation, and an arm coupled to the support shaft forco-rotation with the support shaft and the second pawl.
 13. The cuttingtool of claim 12, wherein the actuator includes a first cam lobeengageable with the lever when in the second position, and a second camlobe engageable with the arm when in the second position.
 14. Thecutting tool of claim 11, further comprising a first trigger operable toactivate the motor, and a second trigger operably coupled to theactuator for moving the actuator between the first and second positions.15. The cutting tool of claim 14, wherein the second trigger ispositioned proximate the first trigger such that an operator can graspthe first and second triggers with a single hand.
 16. The cutting toolof claim 14, wherein the second trigger is pivotable between the firstand second positions.
 17. The cutting tool of claim 6, wherein theratchet is rotatable in a first direction, against the bias of a spring,in response to actuation of the ratchet mechanism by the motor.
 18. Thecutting tool of claim 1, further comprising: an electronic brakingcircuit for normally providing a braking force to the motor in responseto deactivation of the motor; and a current overload detection circuitfor monitoring an amount of electrical current drawn by the motor whenthe motor is activated; wherein the current overload detection circuitboth deactivates the motor and overrides the electronic braking circuitin response to the motor exceeding a threshold electrical current toprevent application of the braking force to the motor.
 19. The cuttingtool of claim 1, further comprising: a switch electrically connectedwith the motor and actuated between a first position in which the motoris activated and a second position in which the motor is deactivated; acurrent overload detection circuit for monitoring an amount ofelectrical current drawn by the motor when the motor is activated; and areversing circuit for reversing a rotational direction of the motor inresponse to at least one of the motor exceeding a threshold electricalcurrent and the switch being actuated from the first position to thesecond position.
 20. The cutting tool of claim 1, further comprising adirection switch electrically connected with the motor and actuatedbetween a first position in which the motor and the cam are driven in aforward direction, and a second position in which the motor and the camare driven in a reverse direction.